Camouflage foamed polymer with colored pattern mass

ABSTRACT

A foamed elastomeric polymer with a camouflage appearance on its surface and throughout its mass, characterized by distinct, randomly sized regions of various colors, having curved, nonangular borders with substantially no blend of colors, and being free from gas pockets and blisters. A process for manufacturing a foamed elastomeric polymer of the above description.

This is a Division of application Ser. No. 08/045,192, filed on Apr. 13,1993, now U.S. Pat. No. 5,273,697.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to foamed elastomeric polymers with aparticular color scheme, specifically a visual camouflage appearance.More particularly the invention relates to a camouflage patterncharacterized by distinct, randomly sized regions of various colors,each such region having nonangular borders and being a single, uniformcolor with substantially no blending of colors within it, with all colorchanges occurring at interfaces of distinct colored regions. Thematerial is also free from marring by large gas pockets in and on thesurface thereof. The invention further relates to a process formanufacturing the foamed elastomeric polymer.

2. Description of the Prior Art

Foamed materials have long been utilized in the polymers industries.Foamed polymers generally exhibit greater strength than an identicalmass of the unfoamed polymer, and in many cases drastically reduces thethermal conductivity of the material because of the air contained in thecells of the foam.

Camouflage designs for foamed materials are likewise known. Such designsmost frequently are applied by painting the outer surface of the foam.Attempts to achieve an internal camouflage appearance have resultedeither in an unacceptable visual camouflage effect characterized bysmeared, blended colors, or simply alternating bands of color with norandom distribution of distinct areas of color, and thus no camouflageeffect at all.

U.S. Pat. No. 4,417,932 to Brietscheidel et al. discloses a process forproducing sheets of stratified material from synthetic resin foamparticles. Foam particles are scattered onto a conveying means, andsuperficially preheated during conveyance to a temperature between 100°C. and 160° C. The particles are then fed into a free-fall zone, inwhich they are further heated to a temperature of at least 200° C. Afterpiling the particles onto a support surface, a sheetlike layer is formedby compacting the particles, and the sheet is then sized withsimultaneous cooling.

U.S. Pat. No. 4,142,015 to Bienz discloses a thermal and visiblecamouflage for use on military equipment such as tanks. A layer offoamed plastic with a randomly varying insulating effect is applied tothe outer surface of heat-generating equipment. Visual camouflage may bepainted onto the plastic, or coatings under the plastic layer may alsobe used.

U.S. Pat. No. 4,243,709 to Morton discloses a method for makingcamouflage from sheets of multi-colored coated fabric. A film ofcamouflage polyvinyl chloride film is applied to each side of thefabric. The films are formed by applying plastisols of different colorsto a carrier web, then overcoating the colored portions and any uncoatedportions with a plastisol of another color. The films are then bonded tothe fabric and the web is stripped from the outsides of the fabric. Themulti-colored fabrics are cut into sheets which are attached to a net tomake the camouflage screen.

U.S. Pat. No. 3,119,729 to Ljungbo discloses a flameproof camouflage netand method of manufacturing it. An apertured, flameproof sheet ofplastic, or pieces thereof, are bonded by an adhesive to a net.

U.S. Pat. No. 2,054,848 to Bowker discloses a method of coloringthermoplastic materials to simulate the appearance of natural rocks andminerals, such as onyx. The thermoplastic is kneaded at elevatedtemperature with a solvent. The solvent is driven off and the materialis formed into slabs by heated rolls. Coloring agents are applied toeach slab, along with plasticizers as desired. An uncolored slab issuperimposed over the colored slab, and the two slabs are worked byheated rolls until the desired effect is obtained.

A need thus exists for a camouflage material which has a nonrepetitivecamouflage appearance on its surface and throughout its internal masswherein virtually no blending of colors occurs at the interfaces ofdistinct colored regions.

SUMMARY OF THE INVENTION

Applicant has unexpectedly discovered a cross-linked, foamed elastomericpolymer with a nonrepetitive, visual camouflage appearance on itssurface and throughout its internal mass.

Applicant has also discovered a novel process by which a camouflagematerial can be obtained wherein uncured cross-linkable elastomericpolymer pieces are first compounded in a mixing means with a foamingagent, commonly referred to in the art as a "blowing agent," across-linking agent, and coloring compounds. The resulting coloredbatches of polymer, having the blowing agent and cross-linking agentinternally dispersed, are then cut into small pieces or strips of adesired size with a cutting means. Finally, the colored pieces are curedby foaming and cross-linking. This is accomplished by compressing thematerials in a curing means to a pressure of up to about 2000 psi (144kg_(f) /cm²) while heating to a temperature of between about 100° C. andabout 500° C. During the curing step, the cross-linking and blowingagents which have previously been compounded into the polymer pieces areactivated. The cross-linking of polymer molecules creates a rigid,unified material from the separate polymer pieces. The blowing agent,upon decomposition, creates gas bubbles which effect a foamed, cellularstructure within the material. The materials are then depressurized, andthe cured, foamed material is recovered from the curing means andcooled.

A third embodiment of the present invention is a novel material having avisual camouflage appearance obtained by the process comprisingcompounding uncured batches of the polymer in a mixing means with ablowing agent, a cross-linking agent, and coloring agents to obtaincolored, uncured polymer pieces with internally dispersed blowing andcross-linking agents. The colored, uncured cross-linkable elastomericpolymer pieces are fed into a curing means and cured by foaming andcross-linking the colored polymer pieces. This is achieved bycompressing the materials in the curing means to a pressure of up toabout 2000 psi (144 kg_(f) /cm²) while heating to a temperature ofbetween about 100° C. and about 500° C. The materials are then cooledand depressurized, and the cured, foamed material is recovered from thecuring means.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofa preferred embodiments of the invention, will be better understood whenread in conjunction with the appended drawings in which:

FIG. 1 is a graph of pressure and percentage of cross-linking versustime, illustrating the interaction between the rate of cure and the rateof decomposition of three blowing agents which decompose at differentrates.

FIG. 2 is a graph of pressure and percentage of cross-linking versustime illustrating the interaction between the rate of decomposition of asingle blowing agent and three different, successively faster curerates.

DETAILED DESCRIPTION OF THE INVENTION

The camouflage material of the invention constitutes foamed polymersmade from cross-linked elastomeric polymers. More particularly, they area foamed polymeric material, made from cross-linked elastomeric polymer,having a nonrepetitive camouflage appearance on its surface andthroughout its internal mass. It is distinguished from the prior art inthat it has a nonrepetitive, visual camouflage appearance throughout itsentire structure.

The novel material of the invention has a high-quality visual appearanceand its shock-absorbing and thermal capacity as a foam renders ituniquely advantageous for many commercial applications. It may be usedas insulation in, for example, clothing and beverage can holders, asbody protective gear such as helmets, in a wide variety of sportinggoods such as foamed diving suits, hunting equipment, and in protectivesport padding equipment such as for baseball and football, in footwear,and in military equipment, besides many other uses where a camouflageappearance is desired.

The camouflage material is preferably produced by a curing procedurewhich involves controlling the rheological properties of the polymer andthe relationship between the cure rate and the blowing agentdecomposition rate. Control of relationship between the cure rate andthe blowing agent decomposition rate enables one skilled in the art toavoid both blistering and an unacceptable blending of colors in thematerial. The process consists of the following steps: compoundinguncured polymer batches by mixing the blowing, cross-linking, andcoloring agents with the polymer in a mixing means, cutting the batchesof colored polymer into small pieces, feeding the colored, compoundedpieces into a curing means, curing them with heat and pressure for adesired time period, depressurizing the cured material, and removing thecured material from the curing means and cooling it.

The process begins by mixing the uncured polymer to be foamed with theblowing agent, the curing agent, and coloring agents to form batches ofvarious colors of foamable, cross-linkable elastomeric polymer. Theuncured cross-linkable elastomeric polymer can be selected according tothe properties desired for the final product. Any foamable elastomericpolymer may be used. Uncured polymers commonly used include but are notlimited to polyurethane, polyethylene, polypropylene, neoprene,isoprene, ethyl vinyl acetate copolymer (EVA), butadiene-acrylonitrilecopolymer (NPR), and styrene-butadiene copolymer (SBR) and mixturesthereof. Halogenated derivatives of the foregoing polymers are alsoacceptable, as well as mixtures thereof. While specific polymer specieshave been recited, it should be recognized that other polymers may alsobe acceptable without departing from the spirit and scope of theinvention.

The foamable polymer pieces may be compounded in batches of variouscolors in a conventional mixing apparatus, such as Banbury mixer, andcalendared to form sheets of different colors. To obtain pieces ofdiffering sizes and shapes, a rotary cutter with a variable knife speedand a feeder with a strip cutter and variable speed and feeding angleare used. Other methods of preparing the polymeric pieces may be usedwithout departing from the scope of the invention. Extrusion, forexample, may be used to obtain fixed cylindrical or amorphous pieces toresemble pebbles, streaks, and other structures.

In the art of foamed polymers the use of blowing or foaming agents iswell known. Any blowing agent acceptable in this art may be used in thenovel process described herein. Azo compounds, N'-nitroso compounds andsulfonyl hydrazide compounds are three particularly preferred types ofblowing agents. Furthermore, mixtures of these groups of compounds mayalso be used herein. Among azo compounds, azodicarbonamide,azobisisobutyronitrile, and diazoaminobenzene are preferred blowingagents. Among the nitroso compounds, N,N'-dimethyl,N,N'-dinitrosoterephthalamide, and N,N'-dinitrosopentamethylenetetramineare preferred blowing agents. Exemplary sulfonyl hydrazide blowingagents include: benzenesulfonyl hydrazide, toluene-(4)-sulfonylhydrazide, benzene-1,3-disulfonylhydrazide,diphenylsulfon-3,3'-disulfonyl hydrazide, and4,4'oxybis(benezenesulfonyl hydrazide). Mixtures of the blowing agentsmay also be used.

A wide variety of cross-linking agents may also be used includingwithout limitation organic peroxides such as dicumyl peroxide. Otherknown cross-linking agents may also be used, such as rubber vulcanizingagents.

In addition to the coloring, blowing, and cross-linking agents,additional materials may also be compounded into the uncured polymerbatches in order to modify the rheological properties and the activationof the blowing agent and curing agent of the foamed polymer. Theseadditional materials may include viscosity-modifying agents, dispersionagents, blowing agent activators, cross-linking agent activators, andfillers. These agents are useful to enable one skilled in the art todesign a compound which will produce a foam with a desired texture andappearance in accordance with the process here disclosed.

Exemplary viscosity-modifying agents include natural rubber and otherpolymers with high viscosity. They are added in amounts up to about 30%by weight, preferably up to about 25% by weight, and more preferably toabout 20% by weight.

Exemplary dispersion agents include stearic acid and other surfactants,added in amounts of up to about 10% by weight, preferably up to about 5%by weight, and more preferably from about 1% to about 3% by weight.

Exemplary blowing agent activators include zinc oxide, dibasic leadphthalate, ethylene glycol, and urea and derivatives thereof. They maybe added at up to about 15% by weight, preferably up to about 10% byweight, and more preferably up to about 5% by weight.

Exemplary filler materials may be either active or inert. Active fillersinclude metal silicates such as aluminum silicate, added in amounts upto about 50% by weight, preferably up to about 25% by weight, and morepreferably up to about 20% by weight. Inert fillers include metalcarbonates, such as calcium carbonate, added in amounts up to about 60%by weight, preferably up to 55% by weight, and more preferably up to 50%by weight.

Exemplary tackifiers include hydrocarbon resins such as Strukol 60 NSF,added in amounts up to 15% by weight, preferably up to about 10% byweight, and more preferably up to about 5% by weight. Tackifiers alsoalter the rheological properties of the compound. Other tackifiers maybe selected from the group consisting of synthetic or natural resins,olefins, oils, soaps, and derivatives and combinations thereof.

After the uncured polymer pieces are compounded, they are cut into smallpieces by conventional means known in the art, such as a rotary cutter,and then cured. Differently colored compounded polymer pieces are fedinto the curing means and cured by a cross-linking reaction among thepolymer molecules; simultaneously, the blowing agent decomposesexothermically into a gas, increasing the pressure within the mold andalso accelerating the rate of cross-linking. The process can be used toobtain either open-celled or closed-cell foams by partially orcompletely filling the mold, and by heating the material at atmosphericpressure or at higher pressures, respectively. To obtain a closed-cellfoam, the polymer pieces are compressed in the curing means to apressure of between 0 psi and about 2000 psi (144 kg_(f) /cm²),preferably between about 500 psi and about 900 psi, and more preferablybetween 650 psi (45.7 kg_(f) /cm²) and about 750 psi (52.7 kg_(f) /cm²).If an open-cell foam is desired, the curing means is only partiallyfilled and the materials are not pressurized, remaining instead atatmospheric pressure. If desired, an open-celled foam of still greatercell size could be created by curing the material under vacuum (lessthan atmospheric pressure). To activate the cross-linking and blowingagents the materials are heating in the curing means to a temperature ofbetween about 100 degrees C. and about 500 degrees C., preferablybetween about 130 degrees C. and about 200 degrees C., and morepreferably between about 150 degrees C. and about 175 degrees C. Inaddition to curing the material with heat, other means of curing, suchas microwave or similar irradiation, may be used.

The curing step is a critical step in the process. The temperature,pressure and curing time are adjusted for a particular combination ofblowing agent, cross-linking agent, cross-linkable elastomeric polymer,and curing means geometry to vary the rate of cross-linking such thatthe camouflage piece cures completely and has a visual camouflageappearance throughout its mass and contains substantially no blisters.Blisters are void spaces within the foam that substantially exceed thesize of the foam cells. They may be created by blowing agent or airbubbles which become trapped in the polymer during curing. In general,the higher the temperature, the greater is the rate of cross-linking.

The rate of cross-linking and blowing agent decomposition cannot bemeasured directly. A cone rheometer, however, may be used to analyze anelastomeric specimen. This apparatus allows the measurement of smallpressure changes within the polymer while simultaneously measuring thetorque necessary to shear the polymer in an oscillatory manner.

Three particularly important features in the curing step are the rate ofdecomposition of the blowing agent, the rate of cure of the elastomericpolymer, and the rheological properties of the foamed polymer.Variations in rheological properties can be obtained by varying the typeand amount of additives used. Particularly advantageous additives may beselected from hundreds known in the art and available in the market.

The relationship between the rate of cross-linking and the blowing agentdecomposition rate is crucial to proper curing. If the rate ofcross-linking is too slow, the blowing agent will decompose into a highpressure gas before the material has reached an adequate plasticity bycross-linking, which leads to an unacceptable blending or swirling ofthe colors of the polymer pieces as further cross-linking occurs. On theother hand, if the rate of cure is too fast, the colored pieces willprematurely lose their plasticity, becoming too rigid to adhere togetherwhen the blowing agent increases pressure within the material. In thiscase, when the pressure is released and the material is allowed toexpand freely, blisters will be created throughout the material bytrapped air or blowing agent bubbles located in the interstices of thepieces.

The relationship between cross-linking rate and blowing agentdecomposition rate is illustrated in FIGS. 1 and 2. Curve C and point C1in FIG. 1 illustrate the relationship between the rate of blowing agentdecomposition and cross-linking rate. Curve C indicates a blowing agentwhich decomposes after most of the cross-linking has already occurred.Thus the material will be too rigid to expand without blistering becauseof the gases trapped in the interstices of the foam pieces.

An example of a blowing agent and cross-linking curve wherein thematerial is cross-linked too slowly is provided by Curve A and Point A1in FIG. 1. Curve A indicates a blowing agent that decomposes veryrapidly in the curing process. Thus, at pressure P at time T1, verylittle cross-linking has occurred as the blowing agent decomposes. Sincelittle cross-linking has occurred, the material is quite fluid, and asthe blowing agent decomposes throughout the material, the colors aresmeared by small pressure differences among and within the polymerpieces. Smearing is magnified by the heat buildup arising from theexothermic blowing agent decomposition reaction.

By contrast, with the proper selection of polymer, blowing andcross-linking agents, and additives, it is possible to achieve anoptimal cross-linking rate for a particular blowing agent decompositionrate in view of the rheological properties of the polymer. This isindicated by Curve B and Point B1 in FIG. 1. Cross linking hasprogressed to a sufficient point to prevent the polymer pieces frommoving with respect to each other as the blowing agent decomposes. Ithas not, however, progressed too far, and the polymer pieces aresufficiently pliable and display sufficient tackiness to cross-link andadhere properly together without trapping air or gas bubbles. Blisteringwill not occur, and a visual camouflage appearance will be obtainedwithout a blend or smearing of colors and without blistering.

FIG. 2 illustrates how the rate of cure for a particular compound may bemodified with respect to a particular blowing agent system, whichincludes the blowing agent, blowing agent activator, and other additivesselected to affect the curing process such as tackifiers. In Curve E, bythe time the blowing agent has decomposed sufficiently to foam thematerial, cross-linking has already proceeded beyond an excessivestiffening point, and the polymer pieces will be too rigid andinsufficiently tacky to cross-link and adhere together without trappingair or gas, leading to blisters. Curve G, on the other hand, illustratesa curing rate which is too slow, as indicated by point D1. At point D1,very little cross-linking has occurred; the material is very fluid, anda blend or swirl of colors with a poor camouflage pattern will beproduced by further cross-linking. Curve F, by contrast, illustrates across-linking rate which is neither too fast nor too slow; thus, upondecomposition, the blowing agent gases will be dispersed throughout thepolymer, and the medium is sufficiently stiff to prevent a swirl orblend of colors as further cross-linking occurs.

After the curing step is complete, the materials in the curing means aredecompressed, removed from the curing means, and allowed to cool. Theorder of the cooling step, however, is not critical and the material maybe cooled before being removed from the curing means. The decompressionstep functions to remove the blowing agent decomposition gases and airbubbles from the polymer and to halt the cross-linking reaction. It alsofoams the material further as the gases expand the cellular structurecreated by the blowing agent decomposition.

The foamed material may be removed from the curing means manually orautomatically, and the removal may also occur after mechanical orchemical processing occurs, such as drying, cutting or washing.

When the material has cooled sufficiently, the outer skin of the cured,foamed camouflaged material must be removed to reveal the desiredcamouflage pattern. The skin may be removed by any method known in theart, such as cutting, sliding, or grinding, depending on the shapedesired in the final product.

If the elastomeric polymer selected continues to exhibit smearing orblending of colors regardless of cure rates or blowing agent systemsselected, the viscosity at cross-linking temperature of the uncuredelastomeric polymer should be raised to reduce the tendency of thematerial to flow at the higher temperature. This may be done by using anuncured elastomeric polymer with a lower Malt Index (higher viscosity)at cross-linking temperature, or by varying the type and amount ofadditives capable of modifying the rheological properties of thecompound, such as plasticizers, tackifiers, and fillers by way ofnonlimiting example.

By following the above process together with the above describedrelationships, one skillful in the art of compounding foams can, withoutundue experimentation, formulate an acceptable visual camouflagecompound with no blistering or smearing of colors from the manymaterials available in the art, such as blowing agents, activators,plasticizers, polymers, cross-linking agents, etc. The preferred way toobtain the correct formulation is by observing the visual appearance ofthe cured foamed material to determine if either blisters or smearing ofcolors has occurred. If so, the formulation should be adjusted accordingto the above parameters until the desired pattern is obtained withoutblisters or smearing of colors. A cone rheometer is preferentially usedto more accurately control the process.

Prior attempts to obtain such materials like the present camouflagematerial have not been successful. Some of these attempts have resultedin a poor camouflage appearance, both on the surface of the material andthroughout its mass. Other efforts have not produced a noticeablecamouflage appearance at all, characterized by randomly sized areas ofdistinct colors, and being marred by large air pockets, known asblisters. The blister are distributed throughout the material instead ofthe foam with consistent, uniformly sized foam cells. In both cases theappearance of the material renders it commercially unviable.

The following Examples are given to illustrate the invention, but arenot to be limiting thereof. All percentages given throughout thespecification are based upon weight of the base polymer or polymers usedunless otherwise indicated and total 100% of the final product.

EXAMPLE 1

This Example demonstrates the preparation of a camouflage materialaccording to the invention. The following materials were used in theamounts recited:

    ______________________________________                                                                Parts                                                                         By Weight                                             Material     Object           A      Range                                    ______________________________________                                        Ethylene vinyl acetate                                                                     Elastomeric polymer                                                                            100    100                                      (18% vinyl acetate                                                            content)                                                                      Natural Rubber                                                                             Viscosity modifier                                                                              5      5-20                                    Aluminum Silicate                                                                          Active filler to  10     0-20                                                 reinforce and to                                                              increase viscosity                                               Calcium Carbonate                                                                          Inert filler to lower costs                                                                     10     0-50                                                 costs and increase viscosity                                     Dicumyl peroxide                                                                           Cross-linking agent                                                                             1     0.5-1.5                                  Azodicarbonamide                                                                           Blowing agent     6     0.1-10                                   Zinc Oxide   Blowing agent activator                                                                         5     1-8                                                   to accelerate                                                                 decomposition rate                                               Stearic Acid Dispersion agent  1     1-3                                      Strukol 60 NSF                                                                             Tackifier; homogenizes                                                                          3     0-6                                                   and improves cell quality                                        Coloring Agents                                                                            To impart camouflage                                                                            1     0.1-5                                                 colors                                                           ______________________________________                                         Column A shows parts by weight for Example 1                                  Range Column shows an acceptable, nonlimiting range for each for each         additive to illustrate their effects                                     

A batch of foamable polymer is prepared separately for each colordesired in the final material by weighing the polymer, blowing agent,cross-linking agent, coloring agent, and other materials and mixing themseparately by conventional methods, for example a Banbury mixer, mixingmills, or other methods known in the art, to obtain different batches ofcolored, uncured elastomeric polymer compound. Each colored batch isthen formed into pieces of a specific and proportional size, shape, andweight, according to the final camouflage pattern desired.

For this example, a batch for each of four colors was compoundedseparately in a Banbury mixer and calendared to form thin sheets ofdifferent colors: black, dark green, light green, and beige. To obtainpieces of differing sizes and shapes, a rotary cutter with a variableknife speed and cutting angle were used. By this means, there may beobtained pieces with a wide range of shapes and sizes, such as squares,rectangles, trapezoids or narrow strips. In this example, narrow stripswere cut in the following sizes: black, 800×25×0.6 mm.; dark green,800×25×1.8 mm; light green, 800×25×1.8 mm; beige, 800×25×1.8 mm.

The colored pieces were then arranged lengthwise forming groups in thefollowing pattern: one light green, 1 black, 1 beige, 1 black, one lightgreen, one black, and 1 dark green. This ratio corresponds to the finaldesired camouflage pattern of 40 percent light green, 20 percent darkgreen, 20 percent beige, and 20 percent black.

This ratio was used to obtain a realistic sylvan camouflage pattern. Aflat compression mold 900×600×9 mm was filled with 5.5 kilograms of thecompound according to the above arrangement. The preferred way of curingthe compound is by compression molding. The curing parameters used were60 kilograms force per centimeter squared (60 kg_(f) /cm²), 165 degreescentigrade (C), and a 12 minute batch curing time. At the beginning ofthe cycle, the mold was pressure-purged by applying a pressure of 60kg_(f) /cm² to the mold and releasing it to remove trapped air from thecompound. The pressure of 60 kg_(f) /cm² was reapplied, the material washeated to 165° C., and the compound was cured for 12 minutes, duringwhich time the blowing agent decomposed. The pressure was then released,allowing the cured polymer to expand, and the material was removed fromthe mold and cooled.

This process yielded a micro-cellular expanded foamed slab with noblisters and no smearing of colors. Other suitable methods of curing,such as rotocuring, may be used without departing from the scope of theinvention. The final appearance of the slab was also evaluated byremoving a thin sheet 1.5 millimeters in thickness, which was slicedfrom the slab with a splitting machine. The surface of the internalmaterial exhibited a camouflage effect with no blistering and nosmearing of colors. The sample material was used to fabricate bottleprotectors, masks, to cover helmets, canteens, and boats. The materialwas readily moldable and easily applied to other objects.

EXAMPLE 2

A second batch of foamed polymer was prepared using identical amounts ofall components except dicumyl peroxide (the cross-linking agent), whichwas used at 0.5 parts instead of 1 part. The identical procedure wasfollowed to create a foamed polymer which exhibited a smearing ofcolors. This is in accordance with the disclosed relationship betweenthe rates of cross-linking and blowing agent decomposition. The slowercross-linking rate resulted in a material having relatively littlecross-linking as the blowing agent decomposed. As a consequence, thecolors were smeared by small, localized pressure differences within andamong the polymer pieces.

EXAMPLE 3

A third batch of foamed polymer was prepared using identical amounts ofall components in Example 1 except dicumyl peroxide (the cross-linkingagent), which was used at 2 parts by weight instead of 1 part. Aprocedure identical to that for Example 1 was followed, yielding a batchof polymer with high levels of blisters in the material, in accordancewith the disclosed relationship between the rates of cross-linking andblowing agent decomposition. The faster cross-linking rate resulted in amaterial having a relatively great amount of cross-linking as theblowing agent decomposed. Consequently, the material was relativelyrigid at the point of blowing agent decomposition, creating pockets oftrapped gas which were not dispersed throughout the medium. Upondepressurization, these gas pockets created blisters.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention and all suchmodifications are intended to be included within the scope of thefollowing claims.

What is claimed is:
 1. A foamed elastomeric material having a nonrepetitive, visual camouflage appearance on its surface and throughout its internal mass, made from cross-linked elastomeric polymers by a curing and foaming process, which comprises:a) compounding in a mixing means various batches of materials comprising(1) uncured cross-linkable elastomeric polymer pieces, (2) a coloring agent, each said batch having a single, uniform color, (3) a blowing agent, which during a curing step forms dispersed bubbles within the elastomeric polymer pieces, and (4) a cross-linking agent; b) cutting the compounded batches of uncured polymer into small pieces, c) feeding into a curing means said small pieces of uncured, compounded elastomeric polymer, each of said small pieces having a single, uniform color with different pieces having different colors, d) curing said small pieces of uncured, compounded elastomeric polymer by simultaneously foaming and cross-linking the uncured cross-linkable elastomeric polymer pieces by compressing the materials in the curing means at a pressure of up to about 2500 psi while heating the materials to a temperature of between about 100° C. and about 500° C. to create a cured elastomeric polymer; e) depressurizing the cured elastomeric polymer to remove excess blowing agent bubbles and to foam the material; f) recovering a cured foamed material; and g) removing the outer skin of the cured foamed material to obtain a nonrepetitive, visual camouflage appearance.
 2. The foamed polymeric material of claim 1, wherein the material is used as insulation.
 3. The foamed polymeric material of claim 1, wherein the material is used in beverage can holders.
 4. The foamed polymeric material of claim 1, wherein the material is used in body protective devices.
 5. The foamed polymeric material of claim 4, wherein the body protective device is a knee pad.
 6. The foamed polymeric material of claim 4, wherein the body protective device is an elbow pad.
 7. The foamed polymeric material of claim 4, wherein the body protective device is a helmet.
 8. The foamed polymeric material of claim 1, wherein the material is used in sporting goods.
 9. The foamed polymeric material of claim 8, wherein the sporting goods include water diving suits.
 10. The foamed polymeric material of claim 8, wherein the sporting goods are weapons.
 11. The foamed polymeric material of claim 8, wherein said sporting goods are camouflaged apparel.
 12. The foamed polymeric material of claim 1, wherein the material is used in footwear.
 13. The foamed polymeric material of claim 11, wherein said footwear includes shoes.
 14. The foamed polymeric material of claim 1, wherein the material is used in vehicles.
 15. The foamed polymeric material of claim 8, wherein the material is used in recreational water vehicles.
 16. The foamed polymeric material of claim 1, wherein the material is used in military equipment. 